Because of environmental concerns, transportation and disposal of waste water weighs heavily on the economics of producing gas wells with high water-cut. First, the majority of oil and gas wells in the Gulf Coast region produce from reservoirs which are commonly classified as water-drive type reservoirs. In a water-drive reservoir, the predominant mechanism which forces the movement of oil or gas in the reservoir toward the wellbore is the advancement of a formation water aquifer. The formation water phase is found beneath the oil or gas phase in a "bottom-water" reservoir or on the outer flanks of the oil or gas column in an "edge-water" reservoir. In either case, water moves into the rock pore spaces which were once filled with hydrocarbonaceous fluids in response to continued production of oil or gas.
Over time, this natural water encroachment leads to the advancement of water into the producing interval, and the well eventually begins to produce quantities of formation water. As the influx of water continues in the reservoir, the percentage of produced water, as compared to total fluid production, increases with time. The ever increasing production rate of formation water is undesirable in both oil and gas wells.
In the case of a gas well, the production of even relatively low quantities of formation water can be detrimental to the productivity of the well. When formation water and natural gas enter the wellbore, each fluid phase begins to travel upward toward an environment of reduced pressure at the surface of the well. As pressure decreases toward the surface, gas contained in the well's tubulars expands, and the velocity of the gas increases accordingly. As a result, the expanding gas acts as a carrying mechanism to continually remove the formation water from the well.
However, as reservoir pressure decreases in response to continued gas production and/or water volumes entering the wellbore continue to increase, the ability of the gas to carry and remove formation water from the well is greatly reduced. As this phenomenon begins to occur, the relatively dense formation water begins to "fall back" into the well. Eventually this water will fill the well's tubing to the point that hydrostatic pressure created by the water column approaches the prevailing reservoir pressure. When this occurs, the productivity of the well is significantly reduced. Increasing water encroachment and/or continued pressure declination results in the eventual cessation of production.
Therefore, what is needed is an effective means of producing water-cut gas i.e., gas with water entrained therein which will permit the water phase to be left behind.